Systems and methods herein generally relate to security printing, and more particularly to printed security features that use transparent keys to reveal hidden security markings.
In the area of security printing, documents are protected from copying, forging, and counterfeiting using multiple techniques. Some methods of security printing use standard materials such as papers, inks, and toners; however, more typically security printing requires special and expensive printing materials. Example documents needing security printing include legal documents, negotiable documents, prescriptions, etc., where a user would like to be able to have a high level of confidence that the document is genuine.
Some security features require a screen or key (a screen) to decode. When copying or scanning Correlation Marks (CR) survive and can still be decoded on copies or scans. Further, CR fonts and a decoding key can be used to produce the correlation effect.